


Returning the Favour

by OptimisticLady



Category: Sherlock (TV)
Genre: F/M
Language: English
Status: In-Progress
Published: 2018-08-15
Updated: 2018-12-01
Packaged: 2019-06-27 23:34:20
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 6
Words: 9,463
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15695646
Author URL: https://archiveofourown.org/users/OptimisticLady/pseuds/OptimisticLady
Summary: REWRITTEN & REVISED. What happens to Katrina Jenkins when she meets Sherlock Holmes? Her life goes spiralling into madness, of course. Then the little game of favours begins.





	1. A Brief Encounter

The violin.

A beautiful instrument, and one that Sherlock Holmes' hands knew far too well. It helped to think, and in this case, he was thinking about the rather ridiculous prospect of love. Specifically, being in love with Irene Adler. He supposed it made sense that anybody who found out about the fact he'd saved her life would think that – but Sherlock was not one to fall victim to that dangerous disadvantage, just like The Woman had.

He supposed that she was lucky his phone had made that rather inappropriate sound when she text him her goodbye. It let her know she wasn't going to die.

Of course, John wouldn't have known about any of that, but that meant Sherlock knew about his flatmate's blatant lie about Irene going into witness protection. He didn't blame John for lying, he was trying not to hurt his feelings. Whatever those were.

He paused for a moment, electing to scribble down the notes of the melody he was composing before finally setting down his violin. He stared out the window, wondering what could be going on in London in the month of January. Were people still celebrating the new year? He wouldn't be surprised if they were, Londoners looked for any excuse to drink despite the prices being ridiculously high for a pint.

It seemed as if his curiosity was high enough to warrant him leaving the flat and going for a walk.

He grabbed his coat and scarf, pulling them on and debating whether or not to call up to John and tell him that he was heading out. Then again, there was a good chance John wasn't even in the flat, and Sherlock wouldn't have noticed if he'd come back anyway.

Once outside 221B, Sherlock walked to the south end of Baker Street and continued walking until he came towards Oxford Street. He checked his watch: it was some time past eleven at night, meaning that the busiest street of London was fairly empty apart from the midweek drinkers and late night workers making their towards tube stations and train stations in an effort to get home.

How wonderfully boring it must be to have a regular job that made you work overtime. There was no way on Earth that Sherlock could do that. The same thing over and over? Ha! As if.

Something caught his attention as he wandered past an alleyway. Noises. Not good noises. He sighed, wondering who could have possibly thought it was a good idea to walk down a darkened alley lit by only one dim street light at this time of night. Man or woman, they were an idiot.

Regardless, it gave him something to do.

He turned left and crept down there, and watched the curious sight before him.

There was a woman in trouble – perhaps a few years younger than he was – but she was holding up her own rather well. Her attacker was about the same height as her, and he had a knife against her throat, holding her in an arm lock too.

“I can feel how blunt that knife is...” the woman told him carefully. “The most damage you'll do is put me in A&E, not kill me – I mean, you've fucked my wrist up enough already... You want the bag that badly? Fine.”

She tossed her bag slightly to the right of her, and the minute the man made a move for it, she elbowed him in the stomach so that he doubled over. That was when Sherlock decided to hop in and help.

There was an open skip with a broken shovel in it, and he grabbed that and gave the man a good whack over the head with the spade side of it. He fell to the ground, half conscious, so the woman kicked him in the face and he was out like a light.

In the moment that the woman gathered up her things, Sherlock took the time to survey her.

Long, curly brown hair tied up in a ponytail, tired blue eyes and relatively smart outfit that suggested she worked in an office, but not in one that she liked.

“Cheers for that,” she said to Sherlock, and he grunted in response, turning away. The woman scurried after him. “Oi! Not gonna give me an explanation? And shouldn't we call the police?”

“Why should I? I was bored, and you're an idiot. And the police won't do anything, that man is homeless.” Sherlock stopped on the main street again, waiting for the woman to catch up with him. “Then again, you don't look like an idiot and you certainly don't act like one. My guess would be that you use that alleyway regularly as a shortcut home.”

A half smile appeared on her face as she caught up to him and they carried on walking together. “Huh. Got it in one. Not many people can do that, except...” Now it was her turn to survey him, and Sherlock spotted the recognition in her eyes. “Well, I would say it's a pleasure to make your acquaintance, Mr Holmes, but you wouldn't give me the same courtesy.”

“Hmmm. Definitely not an idiot.”

She rolled her eyes. “Yeah, I got that. Now. Where we going? My flat's the other direction.”

“You said something about your wrist, my flatmate's a doctor. You can put two and two together, yes?”

“I should hope so, considering I work with computers.”

Sarcasm. The lowest form of wit. In this case, Sherlock could forgive it, because this woman hadn't tried to punch him yet.

“Katrina Jenkins, by the way,” she then said. Sherlock made a huffed noise in response. “Wow, you are quite the arsehole…”

“There it is. Took you longer than other people, but we got there...” he almost seemed amused by that. “You're not from around here, are you?”

“Nope. Would you like to guess where from?”

“I'd say Sheffield.”

“Close, but...”

“Chesterfield?”

“Yes. How'd you figure that one out?”

“Your voice holds a hint of an accent on particular words. Not noticeable enough for people to outright think you're not from the South, but noticeable enough to consider the Chameleon Effect.”

“Parents decided to move south when I was about eight,” Katrina said, as they approached Baker Street.

“I really don't care about the details, Miss Jenkins.”

She grimaced. “My boss calls me 'Miss Jenkins,' so Katrina is just fine with me.”

Sherlock shrugged as they stepped up to 221B, and unlocked the door. “Formalities. It's um… it's polite, isn't it?”

“Something like that. Not that I care for politeness half the time,” she said, following him inside and up the stairs.

“Are you sure about that? You were oddly polite to me.”

“You helped me sort of beat up a guy who was attempting to mug me with a blunt knife. I had to be polite,” Katrina replied in a matter of fact voice.

Sherlock smirked as he tossed his coat onto the sofa. “John!” he then called out. “We have a client. Sort of...” He turned to Katrina. “Sit there.” He pointed at the wooden chair by the desk. Katrina gave him an odd look, but went there anyway.

A few moments later, a jumper clad man came trudging into the room. He looked like he had just been about to go to bed.

“What?” he sighed at Sherlock, who gestured with his head towards Katrina. “Really?”

“I'm assuming she has a sprained wrist, but I'd rather have your…  _ professional _ opinion.”

“So she's not a client?”

“No.” Sherlock grabbed his laptop and settled in the blue armchair, pretending to ignore his flatmate and Katrina, but he kept shooting glances at them every now and then while the good doctor fixed up the woman's wrist.

The room was silent, but from every glance Sherlock took at Katrina, he began to learn more and more about her. It took about ten minutes before he cracked and decided to grill her.

“Necklace. Where did you get it from?” he asked her.

“Excuse me?” she jumped, while on her way out.

“Necklace. Tiny diamond, but still too expensive for you to buy on the current wage you earn, although your quite charming two bedroom flat in Brixton says otherwise...”

She didn’t even want to know how he knew about that.

“Not that it's actually any of your business, but the flat in Brixton is cheaper than you think, and necklace was a gift from someone I dated a couple of years ago.” Katrina turned back to John. “Thank you, Dr Watson.”

He smiled. “No trouble at all. Um… see you around?”

“Maybe.” Katrina glanced at Sherlock. “Good night, Mr Holmes. I think I owe you a favour now.”

And with that, she left.

“Take a night bus, would you?!” Sherlock called after her, but she was gone. He scowled at the empty doorway, while John looked at him oddly.

“How did you find her?” he then asked his friend.

“I went for a walk, someone had a knife to her throat.” Sherlock shrugged. “She would have done fine on her own, if I'm honest, but I needed something to do.”

“You'll get a case soon, Sherlock...” John said, getting up. “But for Christ's sake, let me sleep.”

John left the living room and retreated to his bedroom, leaving Sherlock to mull the woman's last words to him over in his mind.

_ I think I owe you a favour now. _

He groaned, realising that he would most likely run into the damn woman again.

Well, at least his life would be a little more interesting on his off days, now.


	2. The Diamond Girl: Excursions

A few days later, things got rather interesting.

Katrina rarely frequented cafes - in fact, she rarely frequented central London outside working hours, except she had fancied an excursion out - but there was one just off of Oxford Street that took her fancy and she decided that instead of getting a coffee to go, she would sit inside instead. It was fairly quiet inside, and Katrina was certain that this particular coffee shop held a slightly more upper class clientele.

As she waited for her beverage to be made, a newspaper caught her attention on the table nearby. She went and sat down, picking it up and reading what was one the front page: apparently there had been several break ins at flats near Brixton, places completely ransacked and yet nothing was taken.

Her eyes narrowed at that, and she sighed, tossing down the paper onto the little table in front of her. Well, she supposed she would have to be on her guard now.

The coffee was brought over to her by the barista, and Katrina thanked him with a smile before going back to brooding over the potential of her flat being broken into. She wondered how high of a chance that would actually happen. There were a lot of flats in the Brixton area that could be utterly turned over.

The real question was what was the point of it all? The police were being as useless as ever with it.

Life in London was never easy, what with all the angry commuters and airhead tourists – crime just added to the throbbing mess of a city. Admittedly, it did make it more interesting, but at the same time… it was something it could use less of.

She stared at the newspaper, sighed once more, and picked it up yet again. She hadn't brought a book with her, and there was hardly going to be signal on her phone at the back of the cafe. Reading useless news about London it was, then. Katrina sipped slowly on her coffee as she did so – it was rather strong, and still quite hot – but it took her all of about forty minutes to finish, including reading the paper from front to back.

When she pushed her cup aside and folded up the newspaper, getting ready to leave, she nearly jumped out of her skin when she saw someone sitting at the table next to her, staring quite intently. Her shock turned to a scowl when she realised who it was.

“Really?” She stood up, picking up her bag and making her way out of the cafe, with Sherlock Holmes hot on her heels. “How did you know I would be here? You literally met me yesterday?”

“What day is it?” he feigned ignorance.

“It's a Saturday.”

“Then it was merely a simple process of deduction. I won't bother explaining it.” Sherlock fell into step beside her, and she sighed.

“The other night I got the impression you like explaining things.”

“I do, but you're not exactly John Watson, are you? You don't particularly care for it.”

She raised an eyebrow at him. “That's because I don't actually know you, therefore I don't care at all.”

There was a slight edge to her voice that made Sherlock curious, but he didn't say anything about it. “You're worried about your flat being broken into.”

“What gave it away?”

“The way you were reading the newspaper.” He completely disregarded the sarcasm in her voice, causing Katrina to roll her eyes.

They crossed the road and made their way towards Oxford Street, causing Sherlock to pull a face. He well and truly hated the busy crowds that wandered the main streets of London on a weekend. Tourists were far too slow and were the bane of his life. Then again, he rarely ever had to deal with them because he got taxis everywhere. Why shouldn't he abandon Katrina and hail one down and go home now?

Oh that was right, because he was going to be polite and accompany her back to her flat, just in case it had broken into.

“I'm actually investigating the break ins,” he then said, trying to make conversation that wasn't small talk. “Had a client come in this morning. Trashed flat and nothing taken, which begs the question: what are the intruders looking for?”

“These break ins have been going on for a week, and you're choosing to investigate now?” Katrina was a bit unimpressed, until a sly look crossed her face. “Which begs the question: what made you want to look into it?”

He smirked. “Very good. How could you tell?”

“Because you clearly don't deal with boring – I've seen the blog, I know who you are. Most people in London – no, the United Kingdom – know who you are, and therefore know you don't do boring!” she snapped. “Now get on with it.” Her voice had completely lost the edge it had previously, which only made Sherlock frown for a moment.

“Jewelry boxes were the only items in bedrooms that were touched. Other trashed rooms included the living room and bathroom. What do you think?”

“They're looking for jewelry?”

“But what specifically?”

“I wouldn't know!” They came up to Oxford Circus and she descended down the steps to the Underground. “Not my area.”

“What is your area?”

“Why are you interested?”

“You're right. I'm not.”

Sherlock then stopped at the top of the stairs leading down, causing Katrina to huff and look back at him.

“What now?”

“Perhaps we take a cab back to Brixton?” he suggested.

“Uh, no. Too expensive. It's about two quid to get from here to home – why are you still here?”

The detective stepped down to her level – even though he was a few inches taller than her. “I told you, I'm investigating the break ins. I had a client this morning, oh do keep up.”

Another eye roll – gosh, this man really was the cause of them, wasn't he? - and Katrina carried on walking down and to the barriers. She pulled out her Oyster card and tapped it on the reader before heading through. She waited for Sherlock to begrudgingly come through and then they went towards the southbound Victoria line escalator

“The tube is too sweaty,” Sherlock remarked, “And I hate it.”

“I agree, but it's the best way for me to get about.”

“So if you live in Brixton, what are you doing up here on a Saturday?”

“It's a nice cafe, and I was bored. Also kind of pricey so tourists avoid it,” she shrugged as they made their way off the escalator and headed onto the platform. “It's fool proof.”

“Hmm. Fair.”

The train came rushing in and slowed to a halt. They didn't talk for the entire journey back to Brixton, not even on the walk back to Katrina's flat. When they were inside, that was when Sherlock piped up.

“Interesting. The client who came to me this morning lives in this building.”

“Perfect, guess I'm getting robbed today.” Katrina approached the elevator and called for it. It was a quick lift, to be fair, and came on its way pretty speedily.

“Not necessarily,” Sherlock pointed out as the doors open and they stepped inside. Katrina pressed the button for the seventh floor and off they went. In silence. Once again.

Getting to the seventh floor, Katrina went towards flat seventy one and pulled out her keys to unlock the door.

Except it was busted.

The pair glanced at each other, and Sherlock lightly pushed the door open.

Katrina was about to protest him doing that, so he held out his arm signaling for her to be quiet. He then pointed at his ear, indicating for her to listen, and she scrunched up her nose, realising what he was getting at and listening out for whatever was happening somewhere in her flat.

They entered directly into the living room and kitchen area, a hallway coming off of it directly in front of them leading towards her bedroom. The source of the noise was coming from the bedroom, clearly.

Katrina glanced towards the kitchen, then nodded with her head at Sherlock to follow her. She then slowly started to sidle her way towards it, her eyes trained on a door in the wall, and Sherlock realised she was aiming to hide in the pantry. He carefully shut the door behind him and went after Katrina.

She opened the pantry door with a slight creak and shuffled inside, Sherlock squeezing in there after her and struggling to close that door properly. After some moving about, they were able to get comfortable, and Sherlock fished his phone out of his pocket and put on the torch light so that they could actually see each other.

They were in very close proximity, and it was all he could do to not whine about it.

“Well now what?” Katrina hissed. “They're probably trashing my bathroom right about now!”

“It's a bit unfortunate, really,” Sherlock replied in an equally low voice. “This isn't random. All these break ins must have been calculated carefully...”

“No kidding!”

“Shh!”

“I'm going to punch you once we get out of here, you understand that, right?”

Sherlock nodded curtly, and Katrina was satisfied with his response.

After that, they waited with bated breath, waiting to hear sounds of the living room being trashed. Except that it never came. Katrina went to speak but Sherlock shook his head at her, so she scowled at him.

Time passed incredibly slowly while they were in there, and Sherlock kept an eye on it on his phone. As soon as fifteen minutes had passed and they had heard nothing, he opened the pantry door and backed out of it into the kitchen.

“Are you going to punch me now?” Sherlock asked, raising an eyebrow at Katrina. She merely shook her head at him as if to say she wasn't actually going to bother, but her obvious annoyance changed to worry and she immediately tackled Sherlock to the floor as a gunshot rang out from down the hallway. They landed in a rather messy heap.

“No, I'm not gonna punch you, but I did just shove you to the floor so that'll have to do for now,” Katrina told him, breathless. “Shall we get out of here?”

“Good plan.”

She rolled off of Sherlock and crawled along the floor and out the door with him not far behind – when in the safety of the hallway, the detective jumped up and helping Katrina to her feet before pulling her along to the stairs and heading up.

“What the – where are we going?!” Katrina wrestled out of his grip as they ran up to the top floor.

“The roof!” Sherlock called back over his shoulder, causing Katrina to stop in her tracks.

“Excuse me?”

He groaned and stopped too, turning to face her. “Do you fancy dying at the age of twenty eight?”

“Twenty seven, and no, I don't!” Katrina then hurried after him as he continued up two more flights of stairs, coming to a halt at the door that led onto the roof. It was held shut by a chain with a padlock. “Now what?”

The sound of foot steps three floors below caused Sherlock to act quickly, and pulled a small leather pouch from his coat pocket. He pulled out some small, thin lengths of metal and started to pick the lock with ease.

Katrina stated at him, completely dumbfounded.

Before she could say anything, Sherlock was pulling the padlock and chain off the handles and they burst through onto the roof, where he swiftly did everything back up again. Soon enough there came an incessant banging of someone trying to get through.

“Now what?!” Katrina cried. We're stuck on a roof with someone trying to kill us! The only way out is down and I really don't fancy dying at twenty eight, there's still far too many people in this world to-”

She stopped herself from finishing the sentence, and Sherlock quirked an eyebrow at her.

“To what?”

“Oh - never mind!” Katrina waved it off as Sherlock turned his attention back to their escape route.

He spun round in a circle with his fingers to his temples a few times with Katrina watching in curiosity until he stopped suddenly, ran, and jumped over to the next building.

Katrina’s jaw dropped.

“Well - come on!”

She took a deep breath, then took a run up and-

There was nothing beneath her feet.

The gap between this building and the next felt way too big.

Somehow, she managed to make it, albeit with a fairly rough landing. Sherlock helped her up once more and off they went, speeding down the fire escape route of the building and once they got onto the street, he hailed down a cab to go back to Baker Street.

**Notes for the Chapter:**

> Hello! Thought I'd chuck the first note in here. This is a rewrite of something I wrote 6 years ago, and I really hope you enjoy it. Any comments left would be much appreciated. I'm crossposting this on here and ffn. So yeah. Happy reading!


	3. The Diamond Girl: Deductions

“I swear to god, I am never, _ever_ following you on a rooftop again. Next time I’ll just take my chances with the scary man with the gun,” Katrina told Sherlock as they walked up the stairs into the living room of 221B.

A rather bemused John looked up from his laptop as they entered. “Oh. Hello again.” 

Katrina gave him a curt nod in response, watching as Sherlock took of his coat and then very abruptly pulled up a chair for her to sit in. She didn’t quite catch onto the fact that that was the point of the chair, until he pointed at it while looking at her.

After she sat down, Sherlock made his way to the blue chair, and John made his way to the red. The surveyed her in silence for some time, the detective with his fingers steepled under his chin, before someone actually said anything. 

“So… what happened on the rooftop?” John asked carefully. 

“Oh!” Sherlock appeared to snap back to reality. “Katrina’s flat was broken into about half an hour ago, and I _finally_ have a theory about what they could be looking for.”

“Really?”

“Hmm. _That._ ” Sherlock once again pointed at Katrina, except more specifically at her neck. She brought a hand up and felt about for her necklace pulling it out from under her collar.

“This? Really? Why? And actually give me a good explanation because I have gone back and forth across London a _lot_ today...” 

“Jewelry boxes were the main target of all the break ins, and they kept happening in your area. You said someone gave it to you that diamond necklace as a gift. What happened to him after that?” Sherlock leaned forward, interested in actually listening to what she had to say. 

“I - well - we broke up a couple of weeks after that. He blocked me on everything but it was odd because apparently he did that to a lot of people, and…” Katrina made eye contact with Sherlock as she came to realise something. “He didn’t do the stereotypical ex thing and block me, did he?”

“Funny how you’re only coming to realise that now,” Sherlock scoffed, causing John to sigh. 

“I’m not one to linger over a break up. I was going to give back the necklace but it’s like he didn’t exist, it was like… he’d been wiped off the face of the Earth.”

“That’s because he was. Going by the fact someone is clearly after it, I’d say he was killed for stealing it. Meaning… hm. Someone really wasn’t very happy about it. But why now?” Sherlock sank back in his seat, pondering over the length of time since the diamond was stolen and the break ins happening to get it back.

“Whoever wants it back probably wants to use it for something?” John offered. Sherlock glanced at him for a second, actually considering what he said.

“What would someone want to use a diamond for?” asked Katrina.

“It’s the hardest known material making it pretty strong and durable, therefore it has the potential to break anything if used correctly,” Sherlock reeled off pretty quickly. “Plus, value.”

“Great. What would someone want to break into with a diamond?”

“Dunno yet. I’m sure it’ll happen soon.” He gave her the most fake, wry smile, that she felt a little bit uncomfortable.

“Again - great. I really wish I didn’t have anything to do with this." 

“Oh, don’t we all. I have to say, Katrina, you’re really dumbing yourself down, aren’t you?” Sherlock said quite suddenly. 

“I - what?” The woman in question appeared to be a little shaken.

“Sherlock…” John warned.

“Bad office job that’s way under your skill bracket, clothes that haven’t been updated in a good four years, and you’re constantly on edge. Not to mention you threatened to punch me, but I think that’s just scratching the surface…”

“So?” Katrina looked offended.

“So what I’m getting at, Katrina, is what’s your deal?” I saw your living room. I know what you can do.”

“My deal, huh? I don’t think that’s any of your business. And as to what you _think_ I can do? Again, find me a job where I can do it and then I’ll upgrade my wardrobe to suit myself,” she snapped back, her nostrils flaring a little as she said that. “And we’re _also_ not going to say a _word_ about what’s in my living room.”

Silence fell in the room. The two men shared a look - one of surprise - before they looked back at Katrina.

“What?” she asked after a moment, her face showing how weirded out she was by the pair of them looking at her like _that._

“Funny. Nobody tells him off,” John replied.

“People need to do it more often. Anyway - back to the point - _what do I do?_ ”

“We need to do more investigating. We need to actually _confirm_ that whoever it is is actually after you,” piped up Sherlock again.

“Are - are you saying I need to wait until somebody tries to come after me again?”

“Precisely. Good, I’m glad you’re catching on,” Sherlock nodded, and Katrina facepalmed.

 “Alright, fine. I guess I should head home now, yeah? I can find your number on your website,” she told him, rising from the chair and smoothing out her coat in the process. Sherlock frowned at that last remark.

 “No you can’t, it’s not on my website.”

 Katrina smirked. “Yeah, I was just saying that. I’ll find it. Don’t you worry. I’ll let you know if anything happens.”

 “Good day, Katrina,” Sherlock muttered as she left.

 When she got out of 221B, Katrina felt as if she could breathe again, letting out a heavy sigh. So the past day had gone from relatively normal to outlandish within the space of a couple of hours - not to mention she needed to clean up her trashed flat - and of course, there was the chance that someone was out to kill her for a _tiny diamond sitting on her neck._

 Speaking of, Katrina hastily tucked that back into her shirt, and made her way to the tube station at the end of Baker Street.

 As she was slowly making her way down the escalator, she popped her earphones in and put on some music in an effort to keep level headed about the situation. She head to the southbound platform for the Bakerloo Line and sat down at one of the few seats, waiting for a train to come.

 She noticed someone hover nearby, but didn’t think much of it because it was a Saturday in London after all, probably just some tourist. Nobody knew the concept of personal space on the Underground.

 A few moments later, the train arrived and she got on, electing to stand rather than sit considering she would be changing to the Victoria line at Oxford Circus for the second time that day to get back to Brixton.

 On the walk through Oxford Circus, she could feel someone walking a little too close to her. Now that was beyond the idea of no personal space. She lightly elbowed whoever it was and quickened her pace, managing to hop onto her next train just before the doors closed. As did someone else, and they went crashing right into her.

“Jesus - mind out, would you?!” Katrina batted the man away from her before going to sit down. As she looked back over at him, he shook his head and went to go sit down himself.

 She turned her music up and kept trying to sneak glances at the man, but to no avail since more people appeared to get on the tube at Green Park. Something seemed off. Katrina could feel it.

 Eventually she got back to Brixton for the second time that day, and feeling eyes on her, Katrina glanced back over her shoulder while walking in the direction of her home - towards the Brixton Academy - that the same man from the tube was close by, watching her. Ripping out of her earphones, Katrina hurried on down the street and made her way back to her flat, keeping as alert as possible at all times.

 She could have been paranoid, but at the same time it was no mere coincidence that it was happening on today of all days.

 Heading back into her rather trashed flat (now with an added gunshot in the door), Katrina slammed the door and dived straight for one of her many laptops on the sofa. She needed to find Sherlock’s number, and right now.

 It didn’t take very long to find. Too easy.

 She whipped out her own mobile phone and shot him text. 

_Was followed to Brixton. Probably being watched.  
_ _-K. A. Jenkins_

_Alright.  
_ _-SH_  

_Also, you were quick on getting my number.  
_ _-SH_

_That’s about as much of a compliment you will get._ _  
_ _-SH_

Despite everything, a small smile came to Katrina’s face. Small victories were worth something. She wasn’t trying to impress him by any means but _damn,_ the validation was good, as annoying as he was.


	4. The Diamond Girl: Detective Work

Sherlock had been lying on the sofa, his jacket and shoes removed with his eyes shut in what seemed to be deep thought when his phone vibrated. A half smile appeared on his face as he saw the text was from Katrina, and he checked his watch.

“Thirty seven minutes to get to her flat from here, and another six to get my number…” he murmured as he replied to her.

“What was that?” John asked from the desk, and Sherlock jumped up, heading over and pulling out a map of London and spreading it out right before his friend.

“It takes thirty six minutes to get from here,” he pointed at the location of their flat on Baker Street, “to here, via the tube and walking for a bit,” he pointed at the general location of where Katrina’s flat was in Brixton.

“And?”

Sherlock blinked. “Well, it took her another six minutes for her to get my phone number.”

“About that - how?” John finally turned away from his laptop to give his full attention to Sherlock.

“...Google?” The detective replied after a moment.

“Sherlock…”

“She’s  _ very _ good with computers.”

“Have you even put your number online?”

“Nope. Just my email.”

“I see.”

“Really?” Sherlock frowned.

“No.”

“I have a feeling that if you gave Katrina the opportunity to do so, she could hack anything she wanted,” Sherlock explained.

John laughed. “ _ Nooo. _ ”

Sherlock’s face said it all, and John became rather serious.

“She can’t.”

“She can. Her living room has a nice little collection of disassembled laptops and what I suspect to be stolen bits of hardware that let her do what she wants,” he paused. “I wouldn’t be surprised if she’s watching us through your webcam right now.”

Now it was John’s turn to jump up from his seat and back away from his laptop.

“Don’t be too alarmed,” Sherlock said. “If she is watching us - I doubt she is, she’s probably clearing up her flat right now - but  _ if _ she is… she’ll have to be wary of Mycroft.”

“Because it would be…  _ very _ illegal for her to do that.”

“Yes. Katrina is more clever than she lets on. Oh!” Sherlock grabbed his phone, and sent another text to the woman in question.

_ What did he look like?  
_ _ -SH _

_ Tall, black hair, kind of cute I guess.  
_ _ -K. A. Jenkins _

Sherlock groaned and tossed his phone back onto the sofa. John watched with a bemused expression. The detective began muttering to himself, something along the lines of  _ “of course she thought he looked cute but that doesn’t help me,”  _ until John cleared his throat. Sherlock stopped in his tracks.

“Well?” The Good Doctor folded his arms.

“We need to get hold of the tube footage from the past hour. Unfortunately that means going to see Lestrade, and it’ll have to wait until Monday.”

“So now what? We do nothing?”

“Exactly that. Tea?”

John frowned. Sherlock never offered tea. “Are you alright?”

“I’m trying to pass the time,” he said, wandering into the kitchen. “Lestrade is back in on Monday - everyone else down at the Yard are  _ idiots. _ ”

He was practically seething at that last part as he flipped the switch on the kettle. Even though Lestrade wasn’t exactly the greatest detective on earth, he was the most bearable. It would be a lot quicker if Lestrade was about.

Sherlock opted for the container of coffee rather than the jar of tea bags, putting a heaped teaspoon of the instant powder into his mug, along with two teaspoons of sugar. The idea of making John a tea was completely forgotten as he poured the finally boiled water into the cup.

He proceeded to his room, slamming the door in the process.

The next two days were going to be painfully boring.

For the most part, Sherlock sulked, and not even John could coax him out of his bedroom. No matter how much knocking or offering of tea, it was near impossible to get Sherlock out.

It got to the point on Sunday evening where John pounded on the door.

“Sherlock for god’s sake! You’re meeting Lestrade  _ tomorrow _ so buck up!” he yelled.

There was some movement from the other side of the door, and the next thing John saw was Sherlock glaring at him, a little unkempt and tired looking, but wearing his best dressing gown over the top of his regular clothes.

“I’ve been thinking,” the detective said, pushing past and out towards the living room, where he promptly began pacing.

“Of course you have…” John muttered, following him into the living room. “Care to enlighten?”

“Why now? Why would someone want the diamond back now after it’s been missing for at least 3 years?” Sherlock’s fingers were steepled under his chin as he walked up and down the room.

“Well… you said yourself that diamond is the hardest material…” John leaned against the kitchen doorway, crossing his arms.

“And?  _ Please _ tell me there was more to that train of thought because that piece of information has been bugging me all last night and all of today!”

“You can only cut diamond with diamond.”

That made Sherlock stop in his tracks, and he turned to his friend slowly.

“ _ Say that again. _ ”

“Uhm,” John cleared his throat, “You can only cut diamond… with… diamond?” After a moment of looking confused, it clicked for him too. “Wait - you don’t honestly think someone wants to use a  _ diamond _ to break in somewhere?!”

“It would be like slicing through softened butter,” Sherlock mused. “It’s unfortunate we don’t know who wants it or for when - something like this is easily preventable.”

“Really?”

“If I were actually working for Scotland Yard,  _ yes. _ ”

“Right, right… Anything else?”

“Hmm, not until tomorrow, no.”

“Okay. Are you going to stop sulking?”

Sherlock raised an eyebrow, which told John everything he needed to know.

While the detective stayed in the living room, occasionally pacing and stopping to look out the window, John headed upstairs and went to bed.

* * *

“Why didn’t you come in on Saturday then?” Lestrade asked as they walked to Baker Street underground. “Could have got this done a lot quicker.”

“You weren’t in, therefore I didn’t want to have to deal with an idiot,” Sherlock replied, hands in his pockets as they headed into the station and over to the booth window.

“How can I help you today?” the person inside the booth clearly did not want to be at work. Lestrade took out his wallet and flashed his ID, making the clerk’s eyes widen. “What can I do for you, Inspector?”

“We need to have a look at security footage from Saturday,” Lestrade told him. “Is there anyone who’s a bit higher up that can we can talk to for that?”

“Um, yeah, I’ll just—”

The lad wandered off to the back of the room and through a door, coming out a different one next to Sherlock, John, and Lestrade, with who appeared to be the manager in tow.

“If you would like to follow me to my office, we can go through Saturday’s footage in privacy there,” she said with a gentle smile.

The group followed the woman through and after squeezing into the fairly cramped office around her desk, a security guard came back with a USB drive that she plugged into her computer.

Sherlock took charge at that point, finding the exact time Katrina entered Baker Street tune station, and keeping an eye out for anyone who was particularly keen in catching up with her.

“There!” Sherlock paused the movie and pointed at a person on the screen. “Matches her description.” He turned to Lestrade. “If you take this, can you find out who he is and what he’s doing?”

“Can all be with you by the end of the day,” the inspector agreed. He took the mouse from Sherlock and closed everything on the computer, taking the USB out of it too. “Sorry for being so vague about this, Miss,” he addressed the woman in charge of the tube station, “but it’s important we do this quickly or someone could get hurt.”

“Murdered,” Sherlock corrected, causing John to sigh. “Katrina could get murdered if she’s not careful. Good day.”

He rose and left the office with difficulty, John and Lestrade muttering apologies to the manager and going after him.

“The sooner you get this to me, the sooner I can let Katrina know,  _ and _ do my own research. There’s more to this than you think, Lestrade, and you are most definitely out of your depth.”

* * *

About two hours later, Sherlock’s phone pinged. As he glanced down at it, a half smile formed on his face.

Lestrade had the person, and was emailing everything over to him. Probably wasn’t meant to do that, but he knew Sherlock wasn’t likely to go all the way down to the Yard.

Jumping off the sofa and going to the desk, Sherlock opened up his laptop and accessed the email, flipping through the PDF document that had been sent to him. He grinned.

This case just got a whole lot better.


	5. The Diamond Girl: Pub

Thursday nights at her workplace usually meant drinks. Sometimes there was a reason, other times there was no reason at all. They all just had to be careful not to drink too much and get a hangover the next day. As to why they didn’t drink on a Friday? Everything in London was more expensive on a Friday. Thursday night was still the cheap night in all pubs, clubs, and bars.

So Katrina thanked her lucky stars as she sipped on her second double Jack and coke of the night that Thursday nights existed. She was sat at a table with the rest of the tech department, having a jolly old chat and bitch about their workplace and how they were treated.

“...Meanwhile you’ve got Kat who is the most ridiculously underpaid of us all!” said Ollie, one of the tech runners. She nearly choked on her drink.

“Excuse me?!”

“Come on, Kat, we all know you’re way better than what you’re paid. If anything, you should be in charge of the whole department.”

“Hmm, Head of IT at a film company? I think I might pass, thanks very much. Besides, Lucas is doing a pretty good job of it…”

“Yeah, even I think you’re being shafted,” said Lucas, and Katrina pouted. “Come on now, you should really talk to HR about getting a pay rise.”

“Which I can’t do until September when my annual review is,” she pointed out. “We’re still in January, come on now.”

Lucas shook his head in disappointment, chugging back some of his beer.

“Besides,” Katrina carried on, straightening up in her seat a little. “I don’t particularly want to draw any attention to myself. And I’d get too angry at all the stupid requests people put in.”

Ollie raised an eyebrow. “You do that anyway.”

Katrina shrugged while the rest of the table laughed, and she couldn’t help but have a little chuckle herself. The people she worked with were good people, and even though she wasn’t a fan of her job and knew she should be higher up, she was still fine where she was.

At least they knew it, too.

A clink and a light plop brought Katrina out of her thoughts.

She looked down into her tumbler and frowned.

“Did - did you just penny me?” She directed the question at Ollie.

He held up his hands in surrender. “Guilty as charged.”

“I haven’t been pennied since-“

“Since I did my masters,” the entire table finished for her.

“Right, Andy wins. Not even eight thirty…” Lucas said, so he and five others all tossed a tenner each down the table to the man in question, who raked it up quite happily.

“Seriously? You took bets on that? I mentioned it one time!” Katrina said, affronted, as she pulled the penny out of her glass and downed her drink. “Now I need another one…”

She got up and headed over to the bar, ordering her third whiskey and coke of the evening. While she was waiting, she casually glanced around the pub and saw something she was not expecting. When she was handed her drink, Katrina gripped it a little too tightly as she wandered over to the back corner to find Sherlock sitting there with an untouched pint.

“Are you stalking me now, is that what this is?”

“Ah! Katrina,” Sherlock threw her a very fake smile to match the fake cheer in his voice. “Didn’t expect to see you here.” He took a sip of the beer and made a face. Not much of a drinker then.

“That’s a lie.”

“Correct. I had to find out where you went on Thursday nights. Care to join?”

Katrina glanced over her shoulder at her colleagues, who seemed not to have noticed her disappearance yet - if they had, they were used to it by now - and sat the opposite side of the booth to Sherlock. There was a folder on the table, which he pushed towards her.

She set down her drink and was about to flip through it when-

“What — the hell?!”

Sherlock and Katrina both jumped as John appeared next to the booth, clearly out of breath.

“What are you… you just… ran off…” he sat next to Katrina and took note of the pint. “Do you want that?”

“Not particularly, I only bought it to blend in,” Sherlock replied.

“Good.” John took the drink and downed at least half of it before he was satisfied.

“Good evening to you too,” Katrina said, finally opening the file. She faltered for a moment. “Sherlock?”

“Yes?”

“Why is this in binary?”

There was an awkward moment of silence where Sherlock attempted to come up with an excuse, but Katrina got there first.

“You have been stalking me!”

“You didn’t reply to my texts!”

“Yeah well, I’ve been- um...”

He raised a questioning eyebrow at her, while John started on the pint again as he watched.

“Busy,” Katrina finished lamely.

“I know.”

She shut the file and tossed it back at the detective, folding her arms and grumbling.

“You had a binary print up in your living room, so I wanted to entertain the fact that you knew it. Not to mention the information in here is extremely sensitive,” Sherlock said quickly.

“Go on.”

“Sebastian Moran is the man after you, and to put it frankly if you don’t hand the necklace over, he will kill you.”

“Who does he work for?”

“The highest paying person.”

“And who’s that?”

“I don’t know. Some things slip under the police radar, and even doing my own research I couldn’t find out.” Sherlock seemed put out by that but if information.

“Are we going to play a game of sitting ducks so that we can find out?”

“No, we’re going to play a game of favours, actually.”

Katrina folded her arms and leaned forward, intrigued. John groaned and downed the rest of the pint.

“Oh?”

“Technically speaking you’re a client of mine, but an unwilling one. I’ll let you off with not paying if you owe me a favour,” Sherlock proposed.

“And if the favour I do for you is so big that you might end up owing me…?”

“That’s why it’s called a game.”

“Right.”

She considered it for a moment before offering out her hand for him to shake, which he did, albeit rather bemused.

“That was… easier than I thought it it as going to be,” he commented. Katrina shrugged.

“I need some form of entertainment, even if it could be a bit dangerous.”

“Katrina, your life is at risk here,” John pointed out. “This isn’t just a form of entertainment - Sherlock, don’t start something like this!”

“His life is on the line here too, depending on how this favour thing goes,” she replied. “John, it’ll be fine. All we needed to do is find out who Moran works for, hand him the diamond, and bish-bash-bosh we’re done and dusted with the whole thing. Simple.”

“Not - not quite that simple…” Sherlock murmured. “But you do make a good point about handing over the diamond - if you’re willing to part with it, why keep hold of it all this time?”

“Because I could get killed if I don’t. There’s a reason I have a degree - I’m clever and I can think.”

“...Point taken. Seriously though, no emotional attachment to it?”

“I thought the guy who gave it to me was ghosting me when he disappeared off the face of the earth, it was the least he could do. Consider it compensation for what I went through.” 

Katrina was so blasé that it made both men frown - how often had she dealt with break ups?

“You staying here for the rest of the night?” John asked.

She got out her phone and checked the time. “I’ll stay for another half hour and then head home. Why?”

“No reason. Be careful on your way home, especially if he followed you last time.”

“Well, I’ve been fine the past few nights John, but thank you for the concern. Really. Now, I should get back to my colleagues…”

On that note, John moved out of the booth so that Katrina could get out. He sat directly opposite Sherlock after that, who was clearly deep in thought. There was delicate knot to his brow and his eyes were twinkling and alert as he slyly watched Katrina go back over to her table.

“When she leaves, so do we,” Sherlock told John quietly.

The doctor looked at him strangely for a moment, before understanding crossed his face. “Gotcha.”

**Notes for the Chapter:**

> Would be super lovely if any comments were left on this :) Hope you all enjoyed!  
> -OL.


	6. The Diamond Girl: Moran

Around about nine o’clock and feeling delightfully buzzed, Katrina and her colleagues decided to call it a night and all head home. Some drank more than others, but because tomorrow was a Friday, any potential headaches in the morning weren’t going to be a problem. Fridays were often slow because nobody cared enough about their computers or their work by the end of the week - deadline depending.

The tube ride home felt a little more wobbly than usual, and Katrina had to fight to not have a tipsy doze, so instead put on some loud music in her earphones until she reached Brixton. If anything, the warmth of the London Underground has made her feel more out of it, but the whack of cold fresh air upon leaving the station brought her back again.

Katrina walked home quickly, the idea of a glass of water and going to bed calling to her like no other. In preparation for getting to bed efficiently, she put her earphones and phone in her coat pocket upon reaching her building.

The moment she stepped into the warm building, she became properly sleepy againa and struggled to put the key in the lock of her front door, after a good thirty seconds she stumbled inside.

Switching on the light, Katrina dumped her coat and bag in the living room before going to get herself a glass of water. She downed that fairly quickly, and headed back into the living room, pulling off her jumper and her shoes.

She went over to the window and opened it. Even though it was January, she needed to cool off from the tube and brisk walk home. She unbuttoned her shirt, peeling it off and feeling much better in her tank top - the cool air swept over her skin and relieved it from the sweaty heat of her clothes.

Katrina stayed by the window, leaning against the wall next to it, shutting her eyes and taking a moment to make sure the room didn’t start to wobble. Perhaps she was more than a little bit tipsy. Perhaps she was drunk.

She was crudely dragged from her thoughts by someone slamming her to the floor by her neck.

Now that sobered her up.

Katrina scrabbled and kicked at the man who had somehow gotten into her flat, managing to get him to loosen his grip on her as she gave him a good whack to the knee. She managed to roll so that she was on top of him, and gave the man a good punch to the face before realising who it was.

Of course, it wouldn’t be anyone else other than Sebastian Moran.

Her momentary lapse of attention meant that Moran had a chance and he shoved her off of him and into the coffee table. Luckily it was only a wooden one so didn’t break into pieces, but instead tip over with Katrina going over the top of it and whacking the back of her head on the corner of the television stand.

Concussed and woozy, Katrina couldn’t react fast enough when Moran took his belt off and promptly wrapped it tight around her throat. She flailed, trying her best to bat him away and then deciding it was probably better to try and hook her fingers under the belt while she was still conscious.

Her face was throbbing as she lost oxygen, and on the cusp of blacking out, Katrina saw her front door slam open - it was Sherlock and John.

Immediately Moran let go of her, and smash to her right told her he had jumped out the window; a resounding crash and an alarm told her he had landed on a car.

She leaned on her elbow, coughing and breathing deeply as she was able to breathe again. Her head was pounding, and fingers on the back of it let her know that John was looking for the damage.

That made her regain her focus, and she jumped up away from him, wobbling slightly so she rested against the wall for support.

“Why - why are you here?” she asked them, but John winced. She’d raised her voice without realising.

“We followed you home,” Sherlock responded calmly.

“Why?” Katrina was getting louder.

“I saw him outside the pub.”

Breathing heavily and shaking, Katrina dropped to the floor and pulled something out from under the sofa - a laptop. She opened it and began furiously typing in silence.

“What are you doing?” John asked.

“Finding out who he’s working for,” she said, her voice back at a normal pitch but raspy. “You should have just left me to do this…”

“Katrina, you need to go to A&E…”

“John,” Sherlock warned, coming towards his friend and pulling him back from the woman.

“No, she needs to-”

“Who’s Jim Moriarty?” Katrina then piped up. The two men looked down at her, surprised. “What?” She stood up again, swaying like before.

“He’s… where did you…?” Sherlock’s brow knotted.

“That’s who Moran works for. So tell me. Who is he? There’s not much about him on there except that he worked in IT for a bit.”

They still didn’t respond, and Katrina’s shaking only got worse. She leaned against the wall again, her teeth chattering. She clenched her jaw, trying to stop it, but that only seemed to make her whole head vibrate.

She didn’t feel good, that much she knew. Katrina did her best to focus on the two men in front of her - what the hell was going on with her? - and then like a light switch, her brain decided it was time for a little sleep...

…And a couple of minutes later, she came to - John was tapping her face, trying to rouse her. She shoved him away and sat up.

“A&E?” John suggested again, albeit with a more forceful tone. Katrina still shook her head, and he sighed. “You’re in shock!”

“No kidding,” Katrina groaned, and then using John’s shoulder as support, stood up. She was completely out of it, and swayed towards Sherlock who helped to steady her. “I’m not staying here tonight. Get me a cab to a hotel?”

“Uh - no,” John said before Sherlock could even say anything. “If you’re staying anywhere, it’s with us.”

The detective rolled his eyes and let go of Katrina, meaning she turned to the other man for support instead. “Not happening,” he said, grabbing the woman’s coat and bag before making his way out of the flat.

Putting his arm around Katrina’s waist, and making sure she was holding onto him, the pair started following after Sherlock. It was surprising how steady on her feet she was, all things considered. They managed to catch the lift before the detective departed in it, and they all went down and out of the building in an awkward silence.

Walking to the main road, Katrina stumbled on the odd occasion, causing Sherlock to get frustrated and help John with her. When they got to the busy road, he used his free arm to hail down a cab, and they three of them got in.

“Just for tonight, and not again,” Sherlock told the other two abruptly. “She can sleep on the sofa.”

Katrina was taken aback. “Cheers, I guess… Guess I still owe you then.”

After that, she slumped with her head falling onto John’s shoulder as they set off for Baker Street, the two men exchanging a look as they both wondered what the hell was going to happen now.

**Notes for the Chapter:**

> Heya! Sorry this is a shorter chapter, but I didn't want to horrifically drag it out. Hope you all enjoyed it regardless, next one should be my normal average chapter length. :)


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